trip, enum and number portability

Nicklas Beijar - TRIP, ENUM and Number Portability

TRIP, ENUM and Number PortabilityTRIP, ENUM and Number PortabilityTRIP, ENUM and Number PortabilityTRIP, ENUM and Number Portability

Nicklas Beijar

[email protected]


CContentsontentsCContentsontents

1. Current situation2. Problem description3. TRIP4. ENUM5. Scenarios6. Number portability7. Conclusions

TRIP, ENUM and Number Portability


CCurrent situationurrent situationCCurrent situationurrent situation

Terminal location• End terminal located with signaling protocol and DNS

”user@host”, ”user@server”• Mapping from name (E.164, URL, e-mail) to address (IP address)

• Mapping stored in location server (gatekeeper, signaling server)• Manually configured or obtained through registration

• Directory servers (ULS, ILS)

E.164 numbers selected for IP Telephony by TIPHON• Can be entered with numeric keypad• Users don’t need to know if the receiver is a IP or PSTN subscriber


CCurrent situationurrent situationCCurrent situationurrent situation

Gateway location• Similar to terminal location, number@gateway• Gateway selected manually by caller or by signaling server• New selection if gateway is unavailable

Number portability• Change service provider, location or service type without changing telephone number • IP Telephony -> number portability between PSTN and IP• Currently available in the PSTN only• Mapping from directory number to routing number (or routing prefix)• Routing number has hierarchy• Mapping performed by Intelligent Network (IN)


Given a phone number corresponding to a specific host on the IP network, determine the IP address of the host. Terminal location problem

Given a phone number corresponding to a terminal on the PSTN, determine the IP address of a gateway capable of completing calls to that phone. Gateway location problem

ProblemsProblemsProblemsProblems


ProblemsProblemsProblemsProblems

• Mappings are not distributed between signaling servers and location servers

• E.164 numbers cannot be used globally

• Users must select gateway manually

• Which gateways are available and suitable for this call?


Gateway selection criteriaGateway selection criteriaGateway selection criteriaGateway selection criteria

• Location• Business relationships• Policies• Features

• Signaling protocol• Codec• Service

• Capacity


TRIPTRIPTRIPTRIP

• Telephony Routing over IP• IETF protocol, still at draft stage• Distributes routing information between location servers

• Information about gateways and the numbers reachable through them• Routes to gateways and signaling servers

• Modeled after BGP-4• Gateway selection driven by policies• Interdomain protocol between Internet Telephony Administrative Domains (ITAD)• Interdomain synchronization based on SCSP and OSPF• Information transported as attributes of the UPDATE message• Expandable


Name Description

Withdrawn routes List of telephone numbers that are no longer available.

Reachable routes List of reachable telephone numbers.

Next hop server The next signaling server on the path towards the destination.

Advertisement path The path that the route advertisement has traveled.

Routed path The path that the signaling messages will travel.

Atomic aggregate Indicates that the signaling may traverse ITADs not listed in the routed path attribute.

Local preference The intra-domain preference of the location server.

Multi exit disc The inter-domain preference of the route if several links are used.

Communities For grouping destinations in groups with similar properties.

ITAD topology For advertising the ITAD topology to other servers in the same ITAD.

Authentication Authentication of selected attributes.

TRIP attributesTRIP attributesTRIP attributesTRIP attributes


Local TRIB

Ext-TRIB

Adj-TRIBs-In(external peers)

Local Routes

Decision Process

Adj-TRIBs-In(internal LSs)

Adj-TRIBs-Out

Local TRIB

Ext-TRIB

Adj-TRIBs-In(external peers)

Local Routes

Decision Process

Adj-TRIBs-In(internal LSs)

Adj-TRIBs-Out

Structure of a TRIP nodeStructure of a TRIP nodeStructure of a TRIP nodeStructure of a TRIP node


TRIP for gatewaysTRIP for gatewaysTRIP for gatewaysTRIP for gateways

• TRIP-GW• Exports routing information from gateways to location server• New attributes

• Circuit capacity• DSP capacity

• Lightweight• Send-only mode• No databases

• Compatibible with TRIP


ENUMENUMENUMENUM

• tElephone NUmbering Mapping• RFC 2916• Maps E.164 numbers into Uniform Resource Identifiers (URI)• The URIs represent different ways to contact a host

• SIP, H.323, TEL, email, ...• Uses the Domain Name System (DNS)

• E.164 number rewritten as a domain name:

+358-9-4515303-> 3.0.3.5.1.5.4.9.8.5.3.e164.arpa


$ORIGIN 3.0.3.5.1.5.4.9.8.5.3.e164.arpa.

IN NAPTR 10 10 “u” “sip+E2U” “!^.*$!sip:[email protected]!” .

IN NAPTR 100 10 “u” “mailto+E2U” “!^.*$!mailto:[email protected]!” .

IN NAPTR 100 10 “u” “tel+E2U” “!^.*$!tel:+35894515303!” .

Example NAPTR recordsExample NAPTR recordsExample NAPTR recordsExample NAPTR records


Sample top level delegations from ITU:3.3.e164.arpa IN NS ns.FR.phone.net. ;France8.5.3.e164.arpa IN NS ns.FI.phone.net. ;Finland

Sample national delegations:5.4.9.8.5.3.e164.arpa. IN NS ns.ServiceProviderX.net.

Sample service provider’s configuration:1.5.4.9.8.5.2.e164.arpa. DNAME 1.5.4.9.8.5.2.ns.hut.fi.

Sample service registrar configuration:*.1.5.4.9.8.5.2.ns.hut.fi. IN NAPTR 100 10 ”u” ”ldap+E2U”\ “$!ldap://ldap.hut.fi/cn=\1!” .

Example reachme serviceExample reachme serviceExample reachme serviceExample reachme service


POTS Phone

Gateway

SIP ClientSIP

Server

DNS

PSTN

IP-basedNetwork

Voice pathENUM query

POTS Phone

Gateway

SIP ClientSIP

Server

DNS

PSTN

IP-basedNetwork

Voice path

LS

Call from IP-based network to PSTNCall from IP-based network to PSTNCall from IP-based network to PSTNCall from IP-based network to PSTN

Location server query (LDAP)


POTS Phone

Gateway

SIP ClientSIP

Server

DNS Server

PSTN

IP-basedNetwork

Voice pathENUM query

POTS Phone

Gateway

SIP ClientSIP

Server

DNS Server

PSTN

IP-basedNetwork

Voice path

Call from PSTN to IP-based networkCall from PSTN to IP-based networkCall from PSTN to IP-based networkCall from PSTN to IP-based network


Number portabilityNumber portabilityNumber portabilityNumber portability

• Scenarios for hybrid PSTN-IP networks:1. The number moves within the PSTN.2. The number moves between PSTN and IP.3. The number moves within the IP network.

• ENUM allows the mapping to be modified at different levels• Another gateway may be more suitable In most cases, information in ALL protocols must be updated


ConclusionsConclusionsConclusionsConclusions

• TRIP solves the gateway location problem• Distributes routing information between location servers

• ENUM solves the terminal location problem• Provides mapping between names to addresses• E.164 numbers

• In the PSTN, number portability implemented with IN• Number portability can be implemented with TRIP and ENUM• Still missing

• Automatic updating of infomation between TRIP, ENUM and IN• Gateway location for the PSTN CTRIP

trip, enum and number portability

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